by By Barbara Surk, Associated Press

by By Barbara Surk, Associated Press

BEIRUT (AP) - Syrian rebels captured most of an oil field in the energy-rich northeast on Thursday, the latest in a string of strategic conquests this week that also included a dam and the defenses around a major airport.

The opposition fighters trying to oust authoritarian President Bashar Assad also captured the town of Shadadah, near the Jbeysa oil field in hotly contested Hasaka province, according to Rami Abdul-Rahman, head of the Britain-based activist group Syrian Observatory for Human Rights.

The oil field is in an energy-rich area along Syria's border with Iraq. Abdul-Rahman said the rebels captured about 70 percent of the oil field but there was still sporadic gunfire in the area.

Opposition fighters were also battling regime forces for the third straight day for control of the main airport in the northern city of Aleppo.

On Wednesday, the rebels knocked down army defenses and closed in on the country's second largest airport in Aleppo, Syria's main commercial hub.

The airport stopped all flights weeks ago because of the fighting.

Earlier this week, rebels captured the nation's largest dam and a military base near Aleppo. They have also brought the fight closer to the heart of Damascus, seat of Assad's regime.

Regime forces carried out airstrikes on rebel position and shelled opposition strongholds with artillery in efforts to counter recent rebel advances in the northeast and around the capital.

The foray in Damascus marks the opposition's second significant attempt to capture the capital since July, when rebels took control of several neighborhoods before being swept out by a swift government counteroffensive.

The Observatory said regime warplanes were pounding rebel positions near Aleppo's international airport on Thursday. Opposition fighters have been attacking the airfield for weeks, and took over most of the "Brigade 80" military base protecting it on Wednesday.

Abdul-Rahman said fierce clashes were also taking place around the airport, which remained in regime hands Thursday. He said there were also reports of heavy fighting at another nearby military air base called Nairab.

The United Nations says nearly 70,000 people have been killed in 23 months of fighting in Syria.

The conflict started as peaceful protests against Assad's rule in March 2011 and turned into civil war after some opposition supporters took up arms to fight a brutal government crackdown on dissent.

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